An internal combustion engine mounted on a vehicle is provided with a variable valve timing device that changes the valve timing (opening/closing timing) of an intake valve and an exhaust valve by changing the rotation phase of the camshaft (camshaft phase) with respect to the crankshaft of the internal combustion engine in order to improve the output, cut down of the fuel consumption, reduce the emission, and the like.
For example, JP-2010-285986A (U.S. Pat. No. 8,166,937B2) shows a hydraulic drive type variable valve timing device. This device is configured to arrange a lock pin that locks the camshaft phase at a predetermined lock phase, and to lock the camshaft phase by releasing the hydraulic oil pressure of the lock pin to move the lock pin toward the lock position and fitting the lock pin to the fitting hole when a lock demand of the camshaft phase occurs during idling operation and the like for example.
Generally, in order that the lock pin can be easily fitted to the fitting hole, a clearance is arranged between the lock pin and the fitting hole. Therefore, in a state the lock pin is fitted to the fitting hole and the camshaft phase is locked, it is possible that the lock pin vibrates inside the fitting hole by the torque fluctuation of the camshaft and the noise (rattling noise) is generated.